Traditional cryogenic helium refrigeration and liquefaction process cycles are designed at a specified maximum capacity operating point. In actual practice, however, the consumer load often varies depending upon the refrigeration and/or liquefaction consumer (heat) loads. Thus, traditional helium process cycle designs and equipment do not always provide the ability to reduce the refrigeration and liquefaction production while maintaining a high operational efficiency. During reduced consumer loads, traditional process cycle designs require maintaining design point operating pressures or allow varying only a limited number of operating pressures of some components. Thus, the actual operating process cycle (also known as the plant) utility requirements (electric power, liquid nitrogen and cooling water requirements) per unit of refrigeration and/or liquefaction delivered by such a traditional plant significantly increases at reduced consumer loads. Common methods of plant capacity reduction use pressure throttling valves, the addition of load using heaters and/or bypassing the cold and/or warm helium gas capacity produced by the components. Although these mechanisms reduce plant production, they have only limited effect on maintaining high plant efficiency. In fact, the implementation of these methods is analogous to driving an automobile with a fully depressed gas pedal while controlling the speed of the vehicle with the foot brake.
There thus exists a continuing need for a helium production and/or refrigeration cycle (sometimes referred to as process cycle herein) and apparatus that while allowing for reduced production maintains a high operating efficiency of a well designed process cycle operating at the required capacity.